Ink-jet recording methods enable highly detailed image recording, employing relatively simple devices and have been applied increasingly to various fields. Further, their uses have been diversified, and recording media or ink-jet inks, which meet specific requirements, have been employed.
In recent years, particularly, the recording rate has been greatly enhanced and ink-jet printers, which exhibit performance durable for the application to shortrun printing, have been developed.
However, in ink-jet printers, in order to bring out demanding performance, ink-jet exclusive paper, provided with high absorbability of ink-jet ink, is required.
When recording is carried out on coated paper and art paper provided with minimal absorbability of ink-jet ink, or plastic film provided with no ink absorbability, ink liquids which differ in color are mixed on the recording medium to result in color contamination, whereby so-called color bleed problems occur. When diversity of ink-jet recording systems is provided for recording media, the above drawbacks remain to be overcome.
In order to overcome the above drawbacks, proposed is a hot-melt type ink-jet recording method in which a hot-melt type ink composition, incorporating waxes solid at room temperature, is employed; the above composition is liquidized via heating; the resulting liquid is ejected via any of the applied energy; and is cooled and solidified after deposition on a recording medium, whereby image recording dots are formed (refer to Patent Documents 1 and 2). Since the above hot-melt type ink composition is solid at room temperature, no staining results during handling. Further, since the ink does not evaporate during melting, nozzle clogging is of no concern. Further, since the ink is solidified immediately after deposition onto the recording medium, it has become known that it is possible to provide excellent printing quality irrespective of paper quality with minimal color bleed.
However, at present, images, which are recorded employing such a hot-melt type ink composition, result in drawbacks such as quality degradation or insufficient abrasion resistance due to raised dots since recorded images are composed of soft, and waxy dots.
On the other hand, disclosed is an ink-jet recording ink which is cured via exposure to actinic radiation (Refer to Patent Document 3). Further, proposed is a non-water based ink in which pigments are incorporated as a colorant; at least three-functional polyacrylates are employed as a polymerizable compound; and ketone and alcohol are employed as a primary solvent (refer to Patent Document 4). Still further, proposed is an ink employing water based UV polymerizable monomers (refer to Patent Document 5).
In these image recording methods, in which curing is carried out via exposure to actinic radiation, the ink itself is cured employing curing components, whereby it has become possible to record images on non-absorptive recording media. However, since a large amount of curing components, other than colorants, is incorporated and such components do not sublime, the resultant recording image surface is raised due to the waxy ink dots, to result in unusual image quality, especially unnatural glossiness.
Further, some of the conventional curing components result in problems in regard to safety. Further, though safety may be secured, problems occur in which it is not possible to freely design physical properties due to the narrow range for selecting materials.
Further, considered as an image forming method, applied to low ink absorptive or non-ink absorptive recording media, is one in which fixing is carried out via incorporation of fixing resins. However, problems occur in which ink ejection properties from ink heads are degraded due to the fixing resins. Still further, the ink incorporating polymerizable compounds, as described above, carries problems in which, during ejection from the ink-jet heads, when retained in the ink standing section for an extended period of time, the ink viscosity tends to vary, whereby when ejected from nozzles, ejection variation occurs due to the viscosity variation of the ink.                (Patent Document 1) U.S. Pat. No. 4,391,365        (Patent Document 2) U.S. Pat. No. 4,484,948        (Patent Document 3) U.S. Pat. No. 4,228,438        (Patent Document 4) Examined Japanese Patent Application Publication No. 5-64667        (Patent Document 5) Japanese Patent Publication for Public Inspection (herein after referred to as JP-A) No. 7-224241        